Multi-sheath delivery catheter

ABSTRACT

A multi-sheath delivery catheter for introducing a prosthesis into a body lumen involving use of (a) an outer sheath containing a portion of the prosthesis and having an inner surface with a non-round cross-section; (b) a middle sheath slideably disposed within the outer sheath and containing another portion of the prosthesis, the middle sheath having a first handle with a non-round cross-section engaging the non-round cross-section of the outer sheath; and (c) a pusher within the middle sheath for engaging the prosthesis, whereby relative rotational movement between the outer sheath and the middle sheath is prevented by virtue of the engagement of the first handle with the non-round cross-section of the outer sheath. In another aspect, the invention provides a delivery catheter having a mechanism for sequentially retracting concentric tubes to deploy the prosthesis. In another aspect, the invention provides a mechanism for preventing relative axial movement of concentric tubes.

This application is a divisional of U.S. patent application Ser. No.08/970,541, filed Nov. 14, 1997 (status: abandoned).

FIELD OF THE INVENTION

This invention relates to the deployment of endoluminal prostheses and,more particularly, to an improved multi-sheath delivery catheter forsuch deployment.

BACKGROUND OF THE INVENTION

Endoluminal prostheses are used for reinforcing or repairing bloodvessels and other lumens within the body. For example, arteries narrowedor occluded by stenosis, thrombosis, or aneurysm may be reinforced, withor without additional surgical procedures such as angioplasty, byplacing a prosthesis in the diseased portion of the artery. Suchprostheses may be deployed within a body lumen by minimally invasiveendoluminal insertion techniques. These include “surgical cut-down”procedures in which a small incision is made in the vasculature, forexample in the femoral artery in the leg or in an artery in the shoulderof a patient, and a catheter is inserted at that location into thevessel. The catheter is maneuvered to the desired point of deployment,and the prosthesis is advanced through the catheter to that point.During this insertion process, the prosthesis is in a reduced diameterconfiguration, smaller than its intended diameter for use in repairingthe vessel. The prosthesis is then expelled from the catheter into thevessel and expanded, with or without additional manipulation, into itsintended use diameter within the vessel. The catheter is then removedfrom the body. Alternatively, percutaneous access may be used, wherein aneedle puncture rather than a surgical incision is used to gain accessto the vasculature. Percutaneous techniques are used for insertingrelatively small prostheses; surgical cut-down techniques are used forrelatively large ones.

A typical known insertion catheter consists of an outer sheath having apusher slidably disposed within it. See, for example, U.S. Pat. No.5,405,377 to Cragg. Once the catheter is inserted in the vessel and theprosthesis is advanced to the desired location within the vessel, thepusher is held in place while the outer sheath is retracted. Thiseffectively discharges the prosthesis from the catheter.

For some prostheses, this simple pusher-in-sheath catheter arrangementis insufficient. An example of such a prosthesis is one having multiplediameters along its axis, such as the bifurcated prosthesis described inU.S. Pat. No. 5,609,627 to Goicoechea et al. The bifurcated prosthesisdescribed in that patent has a stent portion having a first diameteradapted to be disposed in an aorta, and a branch portion having a seconddiameter, smaller than the first diameter, that extends into one of theiliac arteries. To insert such a multi-diameter stent, a multi-sheathdelivery catheter is required.

It is also occasionally necessary to use a multi-sheath catheter todeliver a conventional straight prosthesis. With some prostheses,significant frictional forces exist between the prosthesis and the outersheath of the catheter in which it is contained for transport to thedelivery location and deployment. This may be the case with relativelylong prostheses because friction increases as the outer surface area ofthe prosthesis increases.

A known multi-sheath delivery catheter 10 is illustrated in FIG. 1.Multi-sheath catheter 10, similar to that disclosed in Goicoechea '627,comprises outer sheath 11, middle sheath 12, and pusher 13. Outer sheath11 and middle sheath 12 are designed to be of an optimum diameter forcontaining the aortic portion and one bifurcated leg portion,respectively, of the bifurcated stent described above.

Outer sheath 11, middle sheath 12, and pusher 13 are concentricallyslidably disposed relative to one another and are diametrically sizedsuch that the prosthesis does not buckle against pusher 13 duringdeployment. In order to deploy a prosthesis contained within outersheath 11 and middle sheath 12, catheter 10 is first percutaneouslyinserted to the desired delivery location within a body lumen accordingto methods known in the art. Outer sheath 11 is then retracted whilemiddle sheath 12 and pusher 13 are held stationary. This action releasesthe first portion of the prosthesis that had been contained by outersheath 11 because stationary middle sheath 12 and pusher 13 effectivelyprevent the first and second portions, respectively, of the prosthesisfrom moving as outer sheath 11 is retracted. Outer sheath 11 and middlesheath 12 are then retracted together while pusher 13 is held stationaryto complete deployment of the prosthesis.

During this deployment, it is important that the tubes do not rotatewith respect to one another. Rotation of any one of the tubesindependently along its axis will not rotate the others. Such rotationcould cause twisting or misalignment of the prosthesis being delivered.This also makes it difficult to gauge the twist or orientation of theprosthesis within the catheter, which is critical for aligningbifurcated prostheses with the anatomy. In addition, if the concentrictubes described above are not withdrawn in the proper order, the systemwill not properly deploy the prosthesis. Care must thus be exercised bya physician using a multi-sheath catheter to implant a prosthesis toretract the tubes in proper order.

An improved multi sheath delivery catheter for deployment of endoluminalprostheses is desired.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a multi-sheathdelivery catheter for introducing a prosthesis into a body lumen thathas (a) an outer sheath adapted to contain a portion of the prosthesisand having an inner surface with a non-round cross-section; (b) a middlesheath slideably disposed at least partly within the outer sheath andadapted to contain another portion of the prosthesis, the middle sheathhaving a distal end with a first handle attached to it that has anon-round cross-section corresponding to and engaging the non-roundcross-section of the inner surface of the outer sheath; and (c) a pusherslideably disposed at least partly within the middle sheath and adaptedto engage the prosthesis; whereby relative rotational movement betweenthe outer sheath and the middle sheath is prevented by virtue of theengagement of the non-round cross-section of the first handle with thenon-round cross-section of the inner surface of the outer sheath. Thepusher has a distal end with a second handle attached to it that has anon-round cross-section corresponding to and engaging the non-roundcross-section of the first handle, whereby relative rotational movementbetween the pusher and the middle sheath is prevented by virtue of theengagement of the non-round cross-section of the second handle with thenon-round cross-section of the first handle.

In another aspect, the invention provides a method for introducing aprosthesis to a body lumen using a multi-sheath delivery catheter havingan outer sheath with an inner surface, a middle sheath having a distalend and being slideably disposed at least partly within said outersheath, and a pusher having a distal end and being slideably disposed atleast partly within said middle sheath. The method includes the steps of(a) forming a non-round cross-section in the inner surface of the outersheath; and (b) attaching to the distal end of the middle sheath ahandle that has a non-round cross-section corresponding to and engagingthe non-round cross section formed in the inner surface of the outersheath. The method also includes the step of attaching to the distal endof the pusher a handle that has a non-round cross-section correspondingto and engaging the non-round cross section of the middle sheath.

In another aspect, the invention provides a delivery catheter having aplurality of concentric tubes including an outer tube with an innersurface and an inner tube with an outer surface, at least one of whichtubes is adapted to contain at least a portion of the prosthesis, and afirst protrusion on the inner surface of the outer tube and a secondprotrusion, adapted to engage the first protrusion, on the outer surfaceof the inner tube, wherein the outer tube is adapted to be retractedover the inner tube before engagement of the first and secondprotuberances, and the outer tube and the inner tube are adapted to beretracted together upon the engagement.

In another aspect, the invention provides a delivery catheter having aplurality of concentric tubes including an outer tube having a distalend and an inner surface and an inner tube having a periphery, at leastone of which tubes is adapted to contain at least a portion of theprosthesis during introduction to the body lumen, and (a) at least onenotch on the inner tube; (b) a prong assembly disposed on the peripheryof the inner tube and abutting the distal end of the outer tube, theprong assembly having at least one prong adapted to engage the notch inthe inner tube; (c) a lock ring having a first portion adapted to bedisposed over the distal end of the outer tube and a second portionadapted to be disposed over the prong assembly abutting the distal end;and (d) a protrusion on the inner surface of the outer tube; wherein thesecond portion of the lock ring is adapted to exert a force on the prongassembly sufficient to maintain the engagement of the prong with thenotch and thereby prevent relative axial movement of the inner and outertubes.

In another aspect, the invention provides a delivery catheter having aplurality of concentric tubes including an outer tube having a distalend and an inner tube having a periphery. The catheter also has (a) atleast one notch on the inner tube; (b) a cam-lock assembly having (i) ahub fixedly attached to the distal end of the outer tube; and (ii) acam-lock knob rotationally attached to the hub around the periphery ofthe inner tube; (iii) the cam-lock knob having a detailed inner camsurface adapted to engage the notch in a first position, therebypreventing relative axial motion between the inner and outer tubes, anddisengaging the notch in a second position, thereby permitting relativeaxial motion between the inner and outer tubes.

In another aspect, the invention provides a delivery system forintroducing a prosthesis to a body lumen including (a) a guidewire; (b)a catheter with a lumen adapted to slide over said guidewire, a proximalend, an interior, and a plurality of concentric tubes, at least one ofwhich is adapted to contain at least a portion of the prosthesis duringintroduction to the body lumen; and (c) a nose cone disposed around theguide wire at the proximal end of the catheter, the nose cone having ahole formed through it that is adapted to communicate with both theinterior of the catheter and an ambient environment before insertion ofthe nose cone into the body lumen; whereby the hole allows flushing ofthe catheter to remove air bubbles from the catheter before insertioninto the body lumen.

In another aspect, this invention provides a method for preventingleakage of fluid from an interior of a delivery catheter by disposingthe outer tube on a mandrel having a cross-sectional area substantiallyequivalent to that of the inner tube, applying a compressive force to aportion of the outer tube, heating the outer tube to shrink it aroundthe mandrel, and assembling the outer tube concentrically over the innertube such that a seal is created between the portion of the outer tubeand the inner tube.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view of a portion of a prior art multi-sheath deliverycatheter.

FIG. 2 is a side view of component portions of an exemplary multi-sheathdelivery catheter according to this invention.

FIG. 3 is a side view of the component portions illustrated in FIG. 2assembled into an exemplary multi-sheath delivery catheter according tothis invention.

FIG. 4 is a isometric view of a portion of another exemplarymulti-sheath delivery catheter according to this invention.

FIG. 5 is a partially cut-away isometric view of a portion of anexemplary multi-sheath delivery catheter according to this invention.

FIG. 6 is a isometric view of a component used in another exemplarymulti-sheath delivery catheter according to this invention.

FIG. 6A is a isometric view of a portion of an exemplary multi-sheathdelivery catheter according to this invention.

FIG. 7 is a isometric view of a portion of an exemplary multi-sheathdelivery catheter according to this invention.

FIG. 8 is a partially cut-away isometric view of a portion of anexemplary multi-sheath delivery catheter according to this invention.

FIG. 9 is a isometric view of another exemplary multi-sheath deliverycatheter according to this invention.

FIG. 10 is a side section view of a portion of the exemplarymulti-sheath delivery catheter illustrated in FIG. 9.

FIG. 11 is an end view of the portion of the exemplary multi-sheathdelivery catheter shown in FIG. 10.

FIG. 12 is a sectional detail view of a portion of the multi-sheathdelivery catheter illustrated in FIG. 11.

FIG. 13 is a sectional detail view of the exemplary multi-sheathdelivery catheter shown in FIG. 11.

FIG. 14 is a side view of a portion of another exemplary multi-sheathdelivery catheter according to this invention.

FIG. 14A is a side view of a portion of another exemplary multi-sheathdelivery catheter according to this invention.

FIG. 15 is a side view of a portion of another exemplary multi-sheathdelivery catheter according to this invention.

FIG. 16 is a side view of a portion of another exemplary multi-sheathdelivery catheter according to this invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1 discussed above, the basic components of a knownmulti-sheath delivery catheter include an outer sheath 11, adapted tohold a first portion of a prosthesis to be delivered, a middle sheath12, adapted to hold a second portion of the prosthesis to be delivered,and a pusher 13 for engaging, typically abutting, the distal end of theprosthesis contained within the catheter. Throughout this specification,the term “distal” shall mean “furthest from the heart,” and the term“proximal” shall mean “closest to the heart.” In addition, although twosheaths and one pusher are typically illustrated in the exemplaryembodiments of the multi-sheath delivery catheter of this invention,additional sheaths or pushers may be included and are intended to beencompassed within the scope of the invention described herein. Thesheaths and pushers may generally be referred to as tubes.

In a first aspect of this invention, the inventors have added featuresto a multi-sheath delivery catheter that prevent the sheaths and pusherfrom rotational motion relative to one another, while permitting thesheaths and pusher to slide axially relative to one another. As shown inFIG. 2, the anti-rotation feature involves attachment of a non-roundprofile handle 20 to pusher 13 and a non-round profile handle 21 tomiddle sheath 12. Preferably, handles 20 and 21 have the same non-roundprofile. The same non-round profile is also formed on at least a portion31 (as shown in FIG. 5) of the inner surface of outer sheath 11.Non-round portion 31 may be integral with outer sheath 11 or formed by aseparate member attached to it, such as by molding onto the innersurface. The non-round profile of handles 20 and 21 and of portion 31 onthe inner surface of outer sheath 11 are shown in the illustratedembodiment to be square. Any non-round profile is suitable for purposesof this invention, however, such as triangular, ovular, creased (a“collapsed” circled), or D-shaped by way of example only. Alternatively,another non-round profile handle (not shown) may be attached to outersheath 11 rather than forming the non-round profile on portion 31. Insuch an alternative embodiment, the handle is attached to outer sheath11 as described below.

The tubes of the multi-sheath delivery catheter of this invention aretypically made of polyethylene or other suitable thermoplastic material.Handles 20 and 21 may also be made of polyethylene or other suitablethermoplastic material, or of stainless steel. In the event that handles21 and 20 are formed of the same material as middle sheath 12 and pusher13, respectively, handles 21 and 20 may either be separately formed andattached to middle sheath 12 and pusher 13 or formed integrallytherewith, such as by molding processes known in the art. As analternative, pusher 13 and middle sheath 12 may be formed entirely inthe non-round profile, such that handles 20 and 21 are effectivelysimply the distal ends of pusher 13 and middle sheath 12.

Preferably, handles 20 and 21 are formed of stainless steel and attachedto pusher 13 and middle sheath 12, respectively, which are formed ofpolyethylene. To attach such stainless steel handles to polyethylenetubes, small notches are formed in the proximal end of the handle to beattached to the distal end of a tube. The proximal end of the handle isthen inserted into the distal end of the tube and Teflon heat shrinktubing, known to those skilled in the art, is placed around theoverlapping portions of the handle inside the tube. Upon heating,typically with a heat gun or a lap-welder, to a temperature and for atime period that may be easily optimized by those skilled in the art,the heat shrink tubing shrinks, thereby causing the tube to shrink downinto tight engagement with the steel handle. In addition, thepolyethylene of the tube melts and flows into the notches formed on thehandle. Upon cooling this forms a tight interlocking bond between thetube and the handle. The heat shrink tubing may be removed anddiscarded.

Because pusher 13 typically has a very small internal diameter, it maybe necessary to bore out the distal end of pusher 13 before insertion ofhandle 20 and attachment of the two as described above. Other modularattachment methods may also be used to attach handles 21 and 20 tomiddle sheath 12 and pusher 13, as will be understood by those skilledin the art.

FIG. 3 illustrates the multi-sheath catheter of this invention formedfrom the components of FIG. 2 which have been coaxially assembled. Inthe arrangement shown in FIG. 3, pusher 13 is contained within middlesheath 12, and handle 20 is contained within handle 21. All of the tubesand handles are contained within outer sheath 11. In one finalconfiguration used by a physician to implant a prosthesis, tube 21attached to middle sheath 12 is entirely covered by outer sheath 11.Handle 20 may protrude from the distal end of outer sheath 11 formanipulation by the physician. In another final configuration, handle 21may also protrude from the distal end of the outer sheath 11 formanipulation by the physician. The tubes are all dimensioned such thatthey can all slide axially with respect to one another but, because ofthe non-round profile of handles 20 and 21 and portion 31 of the innersurface of outer sheath 11, the tubes cannot rotate relative to oneanother. Rotation of any of the tubes cause the other tubes to rotatewith it.

Another advantage of this invention is that non-round handles 20, 21attached to pusher 13 and middle sheath 12, respectively, prevent pusher13 from falling out of middle sheath 12 distally, and middle sheath 12from falling out of outer sheath 11 distally.

A visual indicator 25 may optionally be added to the outside of outersheath 11 (or anywhere else along the catheter handles adapted to remainoutside the body into which the catheter is inserted) to illustrate therotational orientation of the endoprosthesis within the deliverycatheter. As shown in FIG. 3, the disposition of a “long leg-short leg”bifurcated endoprosthesis contained within the catheter is visuallydepicted. Absent such visual indicator 25, the only way to determineprosthesis orientation is by interpretation of the position ofradiopaque markers using fluoroscopy. Visual indicator 25 allows thecatheter to be introduced into the body in approximately the correctrotation, requiring less adjustment once inside the patient. Radiopaquemarkers may or may not be used in conjunction with this insertion.

The non-round profile of handle 20, which may be exposed to a physician,provides both tactile and visual feedback to the physician when thecatheter is rotated. The described system makes deployment of theendoprosthesis easier and more controlled by adding stiffness andstability to the handle region where forces are applied. The co-axialhandles 20 and 21 of the system maintain a low profile for the catheterand do not add unnecessary weight or bulk. Using the anti-rotationsystem described above prevents twisting of the endoprosthesis withinthe delivery catheter by preventing the sheaths from rotating relativeto one another, thus preventing deployment of the prosthesis in atwisted configuration.

With a multi-sheath delivery catheter such as that described inconnection with this invention, it is important that sheaths arewithdrawn in the proper order. Otherwise, the system will not deploy theprosthesis. Accordingly, another aspect of this invention automaticallyensures that the retraction of the tubes of the catheter duringdeployment of the prosthesis is performed in the proper sequence;namely, outer sheath 11 is first retracted to release the first,typically larger, portion of the prosthesis, then middle sheath 12retracted to release the second, typically smaller, portion. Withoutsuch a system, middle sheath 12 may be inadvertently retracted beforeouter sheath 11, rendering the delivery catheter inoperable.

This aspect of the invention also allows the physician to perform only asingle, uninterrupted motion to deploy the prosthesis. This helpsprevent deployment errors by allowing the physician to devote moreattention to other aspects of the procedure. Rather than performing afirst retraction motion, removing a lock (for example), and thenperforming a second retraction motion, only a single motion is required.

Sheath sequencing is achieved according to this aspect of the inventionin combination with either an internal or an external locking mechanism,or a combination of internal and external mechanisms, that lock adjacenttubes to one another to prevent relative axial movement until the tubesare unlocked from one another. FIGS. 4 and 5 illustrate a firstembodiment of this aspect of the invention. In this embodiment, thefrictional forces between pusher 13 and middle sheath 12 (and theirassociated handles), and between middle sheath 12 and the prosthesis,are sufficient to prevent undesirable sliding of middle sheath 12 overpusher 13 as outer sheath 11 is being retracted.

FIG. 4 shows the portion of the catheter of this invention where handle20 attached to pusher 13 extends out of handle 21 attached tomiddle-sheath 12. Handle 21 has a protrusion 30 on its outer surface.During deployment, outer sheath 11 (FIG. 5) is retracted over middlesheath 12 and associated tube 21 to deploy a first portion of aprosthesis. During this retraction of outer sheath 11, the frictionalforces between middle sheath 12 and pusher 13 and between middle sheath12 and the prosthesis are sufficient to prevent any relative axialmotion between them.

According to this aspect of the invention, non-round portion 31 of theinner surface of outer sheath 11 is positioned such that upon deploymentof the first portion of the prosthesis, portion 31 (which itself iseffectively a protrusion from the inner surface of outer sheath 11) ofouter sheath 11 engages protrusion 30 on the outer surface of handle 21.By virtue of this engagement, the physician can overcome the frictionalforces between pusher 13 and middle tube 12, and between middle sheath12 and the prosthesis, by continuing to retract outer sheath 11. Thiscauses relative motion between middle sheath 12 and pusher 13. As aresult, both outer sheath 11 and middle sheath 12 are retractedsimultaneously after the engagement of portion 31 with protrusion 30 tocomplete deployment of the endoluminal prosthesis.

Single motion sequenced retraction is thus achieved using this aspect ofthe invention. The physician need only retract one tube (outer sheath11) and proper sequenced tube retraction is automatically ensured usingby virtue of the engagement of portion 31 and protrusion 30.

FIGS. 6-8 illustrate sequenced sheath retraction using a separate prongassembly 40 as an internal lock mechanism in the event that thefrictional forces between the tubes is not sufficient to preventundesirable relative axial movement. As shown in FIG. 6, a prongassembly 40, formed of a thermoplastic material such as polyethylene, orof stainless steel, or of other suitable material, has a cross-sectionalprofile that matches that of handle 20. Prong assembly 40 is adapted tobe disposed around the periphery of handle 20. Prong assembly 40 hasslits 42 formed in the sides thereof and prongs 41 disposed in eachinside corner thereof in the illustrated embodiment. As shown in FIG.6A, notches 49 are formed in the corners of handle 20. Prongs 41 of theprong assembly 40 are adapted to fit into notches 49 when prong assembly40 is disposed on handle 20.

FIG. 7 illustrates the use of prong assembly 40 in accordance with anexemplary embodiment of this aspect of this invention. Prong assembly 40is placed on handle 20 attached to pusher 13 such that prongs 40 fitinto notches 49. A lock ring 43 is then placed over both prong assembly40 and a distal portion of handle 21 attached to middle sheath 12. Lockring 43 serves to maintain the engagement of prongs 41 with notches 49in handle 20. Absent lock ring 43, prongs 41 are easily disengaged fromnotches 49. Lock ring 43 includes a slot 44 which is adapted to allowprotrusion 30 in tube 21 to remain uncovered and to slide relative tolock ring 43 as lock ring 43 is retracted off handle 21 as describedbelow. In the configuration illustrated in FIG. 7, middle sheath 12 islocked from retracting relative to pusher 13 because handle 21 cannotslide over the locked prong assembly 40 attached to handle 20. Thisprevents relative movement between middle sheath 12 and pusher 13.

Lock ring 43 preferably has two portions of separate cross-sectionalareas. The larger cross-sectional area portion is disposed over theperiphery of handle 21, and the smaller cross-sectional area portion isdisposed over the periphery of prong assembly 40. Both prong assembly 40and lock ring 43 must have a wall thickness such that they will fiteasily within outer sheath 11.

FIG. 8 illustrates the use of this internal locking mechanism duringdeployment of a prosthesis according to an embodiment of this inventionwherein the mechanism is used in combination with the sequenced sheathretraction aspect of the invention described above. Outer sheath 11 isretracted until the first, larger diameter portion of the prosthesis isdeployed. At that point, the distal end of portion 31 has engaged theproximal end of lock ring 43 and pushed the small diameter portion oflock ring 43 off prong assembly 40. Because the large diameter portionof lock ring 43 now covers prong assembly 40, there is no forcedengagement of prongs 41 with notches 49 (the large diameter portion oflock ring 43 being sized such that there is space for prongs 41 tobecome disengaged within the large diameter portion of lock ring 43).Prongs 41 are thus released from notches 49 in handle 20. Middle sheath12 is thus unlocked from pusher 13, and these two portions of thecatheter can move relative to one another. Also at this point duringretraction, portion 31 engages protrusion 30 on handle 21, causing thesequenced sheath retraction described above.

FIG. 9 illustrates another embodiment of this aspect of the inventionfor locking tubes together to prevent axial movement relative to oneanother. FIG. 9 shows an assembled catheter according to this inventionwhere the distal end of handle 20 protrudes from the distal end ofhandle 21, which in turn protrudes from the outer end of outer sheath11, which extends into the body of a patient into whom a prosthesis isto be inserted. In this embodiment, cam lock assemblies 50 are disposedat the portions of the catheter where one tube protrudes from another.Cam lock assemblies 50 allow locking and unlocking of the tube fromwhich another tube protrudes and the protruding tube (generally referredto as an outer tube and an inner tube).

FIG. 10 is a side view of one of the cam-lock assemblies 50. Althoughillustrated and described in connection with the locking and unlockingof handles 20 and 21 (and hence pusher 13 and middle sheath 12, any ofthe adjacent tubes may be locked and unlocked using the cam-lockassembly design described below.

As shown in FIG. 10, cam-lock assembly 50 includes a cam lock knob 51and a hub 52. Cam-lock knob 51 is attached to, and pivots on, hub 52which is glued or press-fit (or otherwise fixedly mounted) onto thedistal end of handle 21.

FIG. 11 is an end view of the cam-lock assembly 50 shown in FIG. 10. Asillustrated in FIG. 11 (and in FIG. 9) cam-lock assembly 50 includesindents 59 provided for easy handling and gripping by a physician usingthe device to insert a prosthesis. Also as shown in FIG. 11, and asshown in detail in FIG. 12, cam-lock knob 51 has a detailed inner camsurface 58 that allows respective engagement and disengagement ofcam-knob 51 with notches 57 formed in handle 20.

In the situation illustrated in FIG. 12, inner surface 58 of cam-lockknob 51 extends into notch 57 at A. Inner cam surface 58 then extendsout away from handle 20 at B, creating an open space C between inner camsurface 58 and handle 20. Inner cam surface 58 then contours to thecorner of handle 20 at D, extends away from handle 20 at E, creatinginner space F, then extends into notch 57 in handle 20 at G, extendsback out away from handle 20 at H, creating space I, contours aroundanother corner of handle 20 at J, and extends away from handle 20 at K,creating space L.

By virtue of inner cam surface 58 extending into the notches 57 ofhandle 20 at points A and G, handles 20 and 21 (and hence pusher 13 andmiddle sheath 12) are prevented from axial movement relative to oneanother.

To unlock cam-lock assembly 50 and allow relative movement between tubes20 and 21, cam lock assembly 51 is rotated by a physician (for example)45° counter clockwise from the illustration shown in FIG. 12. The resultis the situation illustrated in FIG. 13. Inner surface 58 of cam-lockknob 51 in FIG. 13 is contoured such that no part of inner surface 58extends into notches 57 of handle 20. Corresponding lettered pointsalong inner surface 58 are shown in FIG. 13 relative to their positionin FIG. 12. As can be seen, each lettered point has rotated 45° counterclockwise such that there is no engagement with notches 57 of handle 20.Accordingly, handle 20 is free to slide axially relative to handle 21,and hence pusher 13 can move axially relative to middle sheath 12.

Using cam-lock assembly 50, middle sheath 12 and pusher 13 may beselectively rigidly fixed and unlocked with respect to one another. Theillustrated embodiment shows handles 20 and 21 having the samecross-sectional shape, but cam-lock assembly 50 can be used when thecross sectional shapes are different. The locking function of cam-lockassembly 50 is accomplished by the detailed inner cam surface 58 ofcam-lock knob 51 which, when locked, engages premachined notches 57 inhandle 20. When cam-lock knob 51 is in the locked position, the twohandles 20 and 21 cannot move axially, or slide, relative to oneanother. Cam-lock assembly 50 becomes unlocked when cam-lock knob 51 isturned counter clockwise approximately 45° in this embodiment, therebydisengaging inner cam surface 58 from notches 57 in inner tubing 20.

Cam-lock knob assembly 50 provides several advantages. First, handles 20and 21 may be rigidly locked with absolutely no axial motion relative toone another by non-frictional means. This is important in an operatingenvironment where contact with bodily fluids could easily disablefrictional locking devices by reducing the coefficient of friction.Thus, accidental unlocking of the device is very unlikely. Second,cam-lock assembly 50 has a “positive feel” in both the locked andunlocked positions and is not easily placed in an intermediate position.Cam-lock knob assembly 50 may be a semi-rigid thermoplastic material,and handles 20 and 21 may be thermoplastic or metallic material, whichallows slight deformations of cam-lock knob 50 to provide user feedbackwith a click or snap when locked. This, along with visual confirmation,lets the user, typically a physician, know whether the device is lockedor not. Third, cam-lock assembly 50 is easy to use and intuitive, whichis critical to the physician operating the device. Cam lock knob 51 mayalso be manufactured with a large grip to provide grip for gloved hands.The intuitive clockwise-lock and counter clockwise-unlock motions arenearly universal and describe a vast majority of screws and fasteners.Lastly, cam-lock assembly 50 has the ability to lock handle 20 in morethan one position if multiple sets of notches 57 are provided. This maybe useful when deploying different sizes of prostheses, for example.Notches 57 in handle 20 may be machined, by methods known to thoseskilled in the art, before the device is assembled. Notches 57 may alsobe molded instead of machined, or cut after assembly but before locking.

According to another aspect of this invention, a seal may be providedbetween outer sheath 11 and middle sheath 12 and between middle sheath12 and pusher 13. Such a seal is desired, for example, to prevent salinesolution from leaking out of the catheter during flushing of the deviceto remove air bubbles. The sealing also prevents blood from escapingfrom the catheter when it is inserted into the patient's body.

The seal is created by applying a radial compressive force to theperiphery of an outer tube while heating it over an inner tube or anappropriately sized mandrel. FIG. 14 illustrates the use of a Teflonheat shrink tubing 60 to provide the radial compressive force duringheating (heat illustrated at 61), which is typically done with a heatgun or a lap-welder. As shown in FIG. 14, tubing 60 is applied overouter sheath 11 which has middle sheath 12 (as opposed to a mandrel)disposed within it. As will be understood by those skilled in the art,the heating should be of sufficient time and temperature (for example,450 degrees F. for 15 seconds) to allow softening of the thermoplasticmaterial of which the outer tube is formed in order to allow it to forma seal with the inner tube as tubing 60 shrinks.

Forming a seal in this manner creates a local region 62 (the regionwhere tubing 60 and heat 61 are applied) where the inside diameter ofouter sheath 11 is very closely sized to the outer diameter of outersheath 12. As shown in FIG. 14A, this creates the desired seal. The sametechnique may be used to form a seal between middle sheath 12 and pusher13 contained within it.

This aspect of the invention provides an efficient, reliable sealbetween the respective parts of the catheter. This is an improvementover simply attempting to manufacture the sheaths of appropriately sizeddimensions. Extrusion, or other formation, to such precise dimensionsthroughout the entire length of the sheaths is not feasible. Because ofmanufacturing variations, the tubes would either be too loose (nosealing) or too tight (excessive sliding friction). This inventionovercomes these manufacturing and use limitations.

According to another aspect of the invention illustrated in FIG. 15, aguide tip 73 with a through-hole 70 for a guidewire is connected to aninner shaft 76 to be contained within pusher 13 of the catheter of thisinvention. Passage of the guide tip 73 followed by the remainder of thecatheter is facilitated by tracking over a guidewire previouslyintroduced into the vessel.

Guide tip 73 is formed of a thermoplastic material, preferably flexible.Front portion 74 of guide tip 73 extends proximally out from outersheath 11 (not shown), while back portion 75 is contained within outersheath 11. A through-hole 72 is formed in guide tip 73. Through-hole 72provides fluid communication between the inside of outer sheath 11 andthe environment.

When the fully assembled catheter is ready for insertion into a patient,immediately before use, the system is typically flushed with salinesolution to remove air from the catheter and prosthesis. Through-hole 72allows the saline solution to be ejected from the inside of outer sheath11 to the environment to insure that the air is removed. Rather thanthrough-hole 72, a groove 79 may be used for the same purpose as shownin the alternative embodiment illustrated in FIG. 16.

Although this invention has been described in connection with certainspecific embodiments, the scope of the invention is not intended to belimited thereto.

What is claimed:
 1. A delivery catheter for introducing a prosthesis toa body lumen comprising a plurality of concentric tubes, at least one ofwhich is adapted to contain at least a portion of the prosthesis, andmeans for sequentially retracting said tubes to deploy the prosthesis,wherein said plurality of concentric tubes includes an outer tube withan inner surface and an inner tube with an outer surface, and said meansfor sequentially retracting said tubes comprises a first protrusion onsaid inner surface of said outer tube and a second protrusion, adaptedto engage said first protrusion, on said outer surface of said innertube, wherein said outer tube is adapted to be retracted over said innertube before engagement of said first protrusion and said secondprotrusion, and said outer tube and said inner tube are adapted to beretracted together upon said engagement.
 2. A delivery catheter forintroducing a prosthesis to a body lumen comprising a plurality ofconcentric tubes, at least a portion of one of which is adapted tocontain at least a portion of the prosthesis during introduction to thebody lumen, wherein said plurality of concentric tubes includes a firsttube having an inner surface, a second tube disposed at least partlywithin said first tube and having a distal end and a periphery, and athird tube disposed at least partly within said second tube and having aperiphery, and means for preventing relative axial movement between saidsecond tube and said third tube, said means comprising: (a) at least onenotch on said third tube; (b) a prong assembly disposed on the peripheryof said third tube and abutting said distal end of said second tube,said prong assembly having at least one prong adapted to engage said atleast one notch in said third tube; (c) a lock ring having a firstportion adapted to be disposed over said distal end of said second tubeand a second portion adapted to be disposed over said prong assemblyabutting said distal end; and (d) a protrusion on said inner surface ofsaid first tube; wherein said second portion of said lock ring isadapted to exert a force on said prong assembly sufficient to maintainthe engagement of said prong with said notch and thereby preventrelative axial movement between said second tube and said third tube. 3.The delivery catheter of claim 2 wherein said protrusion on innersurface of said first tube is adapted to (a) engage said first portionof said lock ring during retraction of said first tube, (b) slide saidfirst portion off said distal end of said second tube, and (c) allowsaid prong of said prong assembly to disengage from said notch, therebyallowing relative axial movement between said second tube and said thirdtube.
 4. The delivery catheter of claim 2 further comprising a pluralityof said means for preventing relative axial movement of said tubes.
 5. Adelivery catheter for introducing a prosthesis to a body lumencomprising a plurality of concentric tubes, at least a portion of one ofwhich is adapted to contain at least a portion of the prosthesis duringintroduction to the body lumen, and means for preventing relative axialmovement of said tubes, wherein said plurality of concentric tubesincludes a first tube having a distal end and a second tube disposed atleast partly within said first tube and having a periphery, and saidmeans for preventing relative axial movement of said tubes comprises:(a) at least one notch on said second tube; (b) a cam-lock assemblyhaving: (i) a hub fixedly attached to said distal end of said firsttube; and (ii) a cam-lock knob rotationally attached to said hub aroundthe periphery of said second tube; (iii) said cam-lock knob having adetailed inner cam surface adapted to engage said notch in a firstposition, thereby preventing relative axial motion between said firstand second tubes, and disengage said notch in a second position, therebypermitting relative axial motion between said first and second tubes. 6.The delivery catheter of claim 5 further comprising a plurality of saidmeans for preventing relative axial movement of said tubes.
 7. Adelivery catheter for introducing a prosthesis to a body lumencomprising an outer tube with an inner surface; an inner tube with anouter surface concentric with said outer tube and adapted to contain atleast a portion of the prosthesis; a first protrusion on said innersurface of said outer tube; and a second protrusion, adapted to engagesaid first protrusion, on said outer surface of said inner tube, saidfirst protrusion and said second protrusion for sequentially retractingsaid outer tube and said inner tube to deploy the prosthesis, whereinsaid outer tube is adapted to be retracted over said inner tube beforeengagement of said first protrusion and said second protrusion, and saidouter tube and said inner tube are adapted to be retracted together uponsaid engagement.
 8. A delivery catheter for introducing a prosthesis toa body lumen comprising a plurality of concentric tubes, at least aportion of one of which is adapted to contain at least a portion of theprosthesis during introduction to the body lumen, wherein said pluralityof concentric tubes includes a first tube having an inner surface and aprotrusion on said inner surface, a second tube disposed at least partlywithin said first tube and having a distal end and a periphery, and athird tube disposed at least partly within said second tube and having aperiphery and defining at least one notch, wherein said catheter furthercomprises: (a) a prong assembly disposed on the periphery of said thirdtube and abutting said distal end of said second tube, said prongassembly having at least one prong adapted to engage said at least onenotch in said third tube; and (b) a lock ring having a first portionadapted to be disposed over said distal end of said second tube and asecond portion adapted to be disposed over said prong assembly abuttingsaid distal end; wherein said second portion of said lock ring isadapted to exert a force on said prong assembly sufficient to maintainthe engagement of said prong with said notch to prevent relative axialmovement between said second tube and said third tube.
 9. A deliverycatheter for introducing a prosthesis to a body lumen comprising a firsttube having a distal end; a second tube concentric with and disposed atleast partly within said first tube and having: (i) a periphery, (ii) atleast a portion adapted to contain at least a portion of the prosthesisduring introduction to the body lumen, and (iii) at least one notch; anda cam-lock assembly for preventing relative axial movement of said firsttube and said second tube, said cam-lock assembly comprising: (i) a hubfixedly attached to said distal end of said first tube, and (ii) acam-lock knob rotationally attached to said hub around the periphery ofsaid second tube, wherein said cam-lock knob has a detailed inner camsurface adapted to engage said notch in a first position, therebypreventing relative axial motion between said first tube and said secondtube, and disengage said notch in a second position, thereby permittingrelative axial motion between said first tube and said second tube.